This invention relates generally to improvements in flexible magnetic disk drive apparatus and more particularly to means useful in such an apparatus to assure proper positioning of a disk carrying cartridge relative to a disk clamp and drive mechanism.
Recently developed flexible magnetic disks are finding increasing applications as a low cost information storage media. Typically, each disk is carried in a flat, rectangular cartridge having a central opening which exposes an annular portion of the disk surrounding a central disk opening. In use, the cartridge is held stationary while the exposed disk annular portion is clamped and rotated. The disk recording surface is accessible through a radial slot formed in the cartridge for reading and writing.
A portion of a typical flexible disk drive system is disclosed in U.S. Pat. No. 3,768,815 which shows a drive shaft coupled to a hub having a cylindrical wall which defines an internal annular recess and a flat face portion. Also included is a rotatable collet for clamping the central annular portion of the disk against the flat face portion of the hub. Thus, as the hub rotates, the clamped disk rotates therewith.
U.S. patent applications Ser. Nos. 522,220 filed Nov. 8, 1974 and 517,542 filed Oct. 24, 1974 by Lewis W. Bleiman disclose a flexible magnetic disk drive system which includes a hinged door opening into a disk cartridge entrance slot. The door is coupled to the disk clamping mechanism comprised of a drive hub and an expandable collet mounted for movement toward and away from the hub. When the door is open, the collet is moved away from the hub permitting a cartridge to be inserted therebetween. When the door is closed, the collet moves into engagement with the hub thereby clamping the disk annular portion against the hub.
It is, of course, important that the disk be seated in its proper position before the door is closed to prevent damaging the disk as the collet and hub move into engagement. Prior mechanisms for avoiding damage to the disk have utilized relatively complex interlock devices which prevent closure of the door unless the cartridge is properly seated.